Steam sterilizers are well known and widely used in hospitals, laboratories, and other facilities for sterilizing and decontaminating many types of articles. For steam sterilizers installed in high-level containment facilities that work with agents that are potentially life threatening, it is important that the doors on the sterilizer be kept sealed in the event of a utility failure, so as to prevent contaminants in the chamber from being released.
In the past, a “passive” or “crush” seal arrangement has been the accepted standard for steam sterilizer door seals. A passive seal is made by mechanically applying a force to the door to force the door into engagement with the sterilizer chamber. Typically, the mechanical force is applied by a manually operated screw mechanism that keeps the door sealed against the sterilizer chamber. A passive seal may pass a vacuum leak test as a result of the chamber door being pulled tightly against a seal by the vacuum, which forces the door into the end frame of the sterilizer. However, once the chamber is pressurized, the door is forced away from the end frame of the sterilizer, which may result in a potential leak around the seal.
Because of the foregoing problem, and because of the cost and complexity of most manually operated mechanical seals, sterilizer technology has moved away from traditional passive seals to “active seals,” wherein an external pressure force, typically steam or air, is used to apply a pressure to accomplish sealing. A problem with active seals is that the seal around the door may be compromised if the external pressure force is lost.
The present invention provides a system for creating an active seal around a door on a steam sterilizer, which system is capable of maintaining a seal for a predetermined period of time even if all customer-supplied utilities to the system are lost.